- rated voltage, capacitance and tolerance of separate series capacitor.
In the documentation can be found:
- weight,
- overall and mounting dimensions,
- power factor (λ, P.F. or cos ϕ),
- compensating capacitor value and voltage for λ = 0.85 or 0.9,
- mains current nominal and during running-up, both with and
without power factor correction,
- watt losses (normally in cold condition),
- description of version, e.g. open impregnated,‘plastic’ encapsulated,
potted or compound filled.
This information suffices to find the right ballast for a certain
application.Additional information can be obtained on request or can
be found in special application notes. Philips ballasts are designed for
use with IEC standardised fluorescent lamps.
Maximum coil temperature t
w
and ∆T
A ballast, like most electrical components, generates heat due to its
ohmic resistance and magnetic losses. Each component has a
maximum temperature which may not be exceeded. For ballasts it is
the temperature of the choke coil during operation that is important.
The maximum permissible coil temperature t
w
is marked on the
ballast. Coil insulating material, in combination with lacquer,
encapsulation material etc., is so chosen that below that temperature
the life specified for the ballast is achieved.A t
w
value of 130 ºC is usual
nowadays with a coil insulating class F (150 ºC) or class H (180 ºC).
Under standard conditions, an average ballast life of ten years may be
expected in the case of continuous operation at a coil temperature of
t
w
ºC.As a rule of thumb,a 10 ºC temperature rise above the t
w
value
will halve its expected life (see Fig. 105). If, for instance, the operating
temperature is 20 ºC above the t
w
value, one may expect a ballast life
of 2.5 years of continuous operation. If no t
w
value is marked on the
ballast, a maximum of 105 ºC is assumed for the coil temperature.
As the ballast normally does not function continuously, the actual life
of the ballast can be very long. It also takes some hours before the
thermal equilibrium is reached in the ballast, which again increases the
practical ballast lifetime.
To verify the t
w
marking, accelerated lifetime tests are done at ballast
temperatures above 200 ºC for 30 or 60 days.
5
111
Fig. 105.The nominal life of choke coils
in relation to the permitted rated
maximum operating temperature of a
ballast winding t
w
, dependent on
insulation material:
a) class A: t
w
105 ºC,
b) class E: t
w
120 ºC,
c) class F or H: t
w
130 ºC.
1.5 Ballast specification and marking
250
200
150
100
0,1
1,0
10
temp. (°C)
t (years)
(c)
(b)
(a)
16
